// Copyright 2015-2019 Parity Technologies (UK) Ltd.
// This file is part of Parity Ethereum.

// Parity Ethereum is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// Parity Ethereum is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with Parity Ethereum.  If not, see <http://www.gnu.org/licenses/>.

use super::{Crypto, Uuid, Version, H160};
use serde::{
    de::{DeserializeOwned, Error, MapAccess, Visitor},
    Deserialize, Deserializer, Serialize, Serializer,
};
use serde_json;
use std::{
    fmt,
    io::{Read, Write},
};

/// Public opaque type representing serializable `KeyFile`.
#[derive(Debug, PartialEq)]
pub struct OpaqueKeyFile {
    key_file: KeyFile,
}

impl Serialize for OpaqueKeyFile {
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
    where S: Serializer {
        self.key_file.serialize(serializer)
    }
}

impl<T> From<T> for OpaqueKeyFile
where T: Into<KeyFile>
{
    fn from(val: T) -> Self {
        OpaqueKeyFile {
            key_file: val.into(),
        }
    }
}

#[derive(Debug, PartialEq, Serialize)]
pub struct KeyFile {
    pub id: Uuid,
    pub version: Version,
    pub crypto: Crypto,
    pub address: Option<H160>,
    pub name: Option<String>,
    pub meta: Option<String>,
}

enum KeyFileField {
    Id,
    Version,
    Crypto,
    Address,
    Name,
    Meta,
}

impl<'a> Deserialize<'a> for KeyFileField {
    fn deserialize<D>(deserializer: D) -> Result<KeyFileField, D::Error>
    where D: Deserializer<'a> {
        deserializer.deserialize_any(KeyFileFieldVisitor)
    }
}

struct KeyFileFieldVisitor;

impl<'a> Visitor<'a> for KeyFileFieldVisitor {
    type Value = KeyFileField;

    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
        write!(formatter, "a valid key file field")
    }

    fn visit_str<E>(self, value: &str) -> Result<Self::Value, E>
    where E: Error {
        match value {
            "id" => Ok(KeyFileField::Id),
            "version" => Ok(KeyFileField::Version),
            "crypto" => Ok(KeyFileField::Crypto),
            "Crypto" => Ok(KeyFileField::Crypto),
            "address" => Ok(KeyFileField::Address),
            "name" => Ok(KeyFileField::Name),
            "meta" => Ok(KeyFileField::Meta),
            _ => Err(Error::custom(format!("Unknown field: '{}'", value))),
        }
    }
}

impl<'a> Deserialize<'a> for KeyFile {
    fn deserialize<D>(deserializer: D) -> Result<KeyFile, D::Error>
    where D: Deserializer<'a> {
        static FIELDS: &[&str] =
            &["id", "version", "crypto", "Crypto", "address"];
        deserializer.deserialize_struct("KeyFile", FIELDS, KeyFileVisitor)
    }
}

fn none_if_empty<'a, T>(v: Option<serde_json::Value>) -> Option<T>
where T: DeserializeOwned {
    v.and_then(|v| {
        if v.is_null() {
            None
        } else {
            serde_json::from_value(v).ok()
        }
    })
}

struct KeyFileVisitor;
impl<'a> Visitor<'a> for KeyFileVisitor {
    type Value = KeyFile;

    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
        write!(formatter, "a valid key object")
    }

    fn visit_map<V>(self, mut visitor: V) -> Result<Self::Value, V::Error>
    where V: MapAccess<'a> {
        let mut id = None;
        let mut version = None;
        let mut crypto = None;
        let mut address = None;
        let mut name = None;
        let mut meta = None;

        loop {
            match visitor.next_key()? {
                Some(KeyFileField::Id) => {
                    id = Some(visitor.next_value()?);
                }
                Some(KeyFileField::Version) => {
                    version = Some(visitor.next_value()?);
                }
                Some(KeyFileField::Crypto) => {
                    crypto = Some(visitor.next_value()?);
                }
                Some(KeyFileField::Address) => {
                    address = Some(visitor.next_value()?);
                }
                Some(KeyFileField::Name) => {
                    name = none_if_empty(visitor.next_value().ok())
                }
                Some(KeyFileField::Meta) => {
                    meta = none_if_empty(visitor.next_value().ok())
                }
                None => {
                    break;
                }
            }
        }

        let id = match id {
            Some(id) => id,
            None => return Err(V::Error::missing_field("id")),
        };

        let version = match version {
            Some(version) => version,
            None => return Err(V::Error::missing_field("version")),
        };

        let crypto = match crypto {
            Some(crypto) => crypto,
            None => return Err(V::Error::missing_field("crypto")),
        };

        let result = KeyFile {
            id,
            version,
            crypto,
            address,
            name,
            meta,
        };

        Ok(result)
    }
}

impl KeyFile {
    pub fn load<R>(reader: R) -> Result<Self, serde_json::Error>
    where R: Read {
        serde_json::from_reader(reader)
    }

    pub fn write<W>(&self, writer: &mut W) -> Result<(), serde_json::Error>
    where W: Write {
        serde_json::to_writer(writer, self)
    }
}

#[cfg(test)]
mod tests {
    use json::{
        Aes128Ctr, Cipher, Crypto, Kdf, KeyFile, Scrypt, Uuid, Version,
    };
    use serde_json;
    use std::str::FromStr;

    #[test]
    fn basic_keyfile() {
        let json = r#"
		{
			"address": "6edddfc6349aff20bc6467ccf276c5b52487f7a8",
			"crypto": {
				"cipher": "aes-128-ctr",
				"ciphertext": "7203da0676d141b138cd7f8e1a4365f59cc1aa6978dc5443f364ca943d7cb4bc",
				"cipherparams": {
					"iv": "b5a7ec855ec9e2c405371356855fec83"
				},
				"kdf": "scrypt",
				"kdfparams": {
					"dklen": 32,
					"n": 262144,
					"p": 1,
					"r": 8,
					"salt": "1e8642fdf1f87172492c1412fc62f8db75d796cdfa9c53c3f2b11e44a2a1b209"
				},
				"mac": "46325c5d4e8c991ad2683d525c7854da387138b6ca45068985aa4959fa2b8c8f"
			},
			"id": "8777d9f6-7860-4b9b-88b7-0b57ee6b3a73",
			"version": 3,
			"name": "Test",
			"meta": "{}"
		}"#;

        let expected = KeyFile {
			id: Uuid::from_str("8777d9f6-7860-4b9b-88b7-0b57ee6b3a73").unwrap(),
			version: Version::V3,
			address: Some("6edddfc6349aff20bc6467ccf276c5b52487f7a8".into()),
			crypto: Crypto {
				cipher: Cipher::Aes128Ctr(Aes128Ctr {
					iv: "b5a7ec855ec9e2c405371356855fec83".into(),
				}),
				ciphertext: "7203da0676d141b138cd7f8e1a4365f59cc1aa6978dc5443f364ca943d7cb4bc".into(),
				kdf: Kdf::Scrypt(Scrypt {
					n: 262_144,
					dklen: 32,
					p: 1,
					r: 8,
					salt: "1e8642fdf1f87172492c1412fc62f8db75d796cdfa9c53c3f2b11e44a2a1b209".into(),
				}),
				mac: "46325c5d4e8c991ad2683d525c7854da387138b6ca45068985aa4959fa2b8c8f".into(),
			},
			name: Some("Test".to_owned()),
			meta: Some("{}".to_owned()),
		};

        let keyfile: KeyFile = serde_json::from_str(json).unwrap();
        assert_eq!(keyfile, expected);
    }

    #[test]
    fn capital_crypto_keyfile() {
        let json = r#"
		{
			"address": "6edddfc6349aff20bc6467ccf276c5b52487f7a8",
			"Crypto": {
				"cipher": "aes-128-ctr",
				"ciphertext": "7203da0676d141b138cd7f8e1a4365f59cc1aa6978dc5443f364ca943d7cb4bc",
				"cipherparams": {
					"iv": "b5a7ec855ec9e2c405371356855fec83"
				},
				"kdf": "scrypt",
				"kdfparams": {
					"dklen": 32,
					"n": 262144,
					"p": 1,
					"r": 8,
					"salt": "1e8642fdf1f87172492c1412fc62f8db75d796cdfa9c53c3f2b11e44a2a1b209"
				},
				"mac": "46325c5d4e8c991ad2683d525c7854da387138b6ca45068985aa4959fa2b8c8f"
			},
			"id": "8777d9f6-7860-4b9b-88b7-0b57ee6b3a73",
			"version": 3
		}"#;

        let expected = KeyFile {
			id: "8777d9f6-7860-4b9b-88b7-0b57ee6b3a73".into(),
			version: Version::V3,
			address: Some("6edddfc6349aff20bc6467ccf276c5b52487f7a8".into()),
			crypto: Crypto {
				cipher: Cipher::Aes128Ctr(Aes128Ctr {
					iv: "b5a7ec855ec9e2c405371356855fec83".into(),
				}),
				ciphertext: "7203da0676d141b138cd7f8e1a4365f59cc1aa6978dc5443f364ca943d7cb4bc".into(),
				kdf: Kdf::Scrypt(Scrypt {
					n: 262_144,
					dklen: 32,
					p: 1,
					r: 8,
					salt: "1e8642fdf1f87172492c1412fc62f8db75d796cdfa9c53c3f2b11e44a2a1b209".into(),
				}),
				mac: "46325c5d4e8c991ad2683d525c7854da387138b6ca45068985aa4959fa2b8c8f".into(),
			},
			name: None,
			meta: None,
		};

        let keyfile: KeyFile = serde_json::from_str(json).unwrap();
        assert_eq!(keyfile, expected);
    }

    #[test]
    fn to_and_from_json() {
        let file = KeyFile {
			id: "8777d9f6-7860-4b9b-88b7-0b57ee6b3a73".into(),
			version: Version::V3,
			address: Some("6edddfc6349aff20bc6467ccf276c5b52487f7a8".into()),
			crypto: Crypto {
				cipher: Cipher::Aes128Ctr(Aes128Ctr {
					iv: "b5a7ec855ec9e2c405371356855fec83".into(),
				}),
				ciphertext: "7203da0676d141b138cd7f8e1a4365f59cc1aa6978dc5443f364ca943d7cb4bc".into(),
				kdf: Kdf::Scrypt(Scrypt {
					n: 262_144,
					dklen: 32,
					p: 1,
					r: 8,
					salt: "1e8642fdf1f87172492c1412fc62f8db75d796cdfa9c53c3f2b11e44a2a1b209".into(),
				}),
				mac: "46325c5d4e8c991ad2683d525c7854da387138b6ca45068985aa4959fa2b8c8f".into(),
			},
			name: Some("Test".to_owned()),
			meta: None,
		};

        let serialized = serde_json::to_string(&file).unwrap();
        println!("{}", serialized);
        let deserialized = serde_json::from_str(&serialized).unwrap();

        assert_eq!(file, deserialized);
    }
}
